Entering the third week after the devastating transmission pipeline explosion in San Bruno, CA, (see NGI, Sept. 13), it appears that additional investigations are likely to come from state regulators and lawmakers, along with various industry assessments.
A California state legislator representing the San Bruno area, Assemblyman Jerry Hill, told the California Public Utilities Commission (CPUC) last Thursday that it is now “crucial that elected officials and regulators ensure the safety of our gas transmission system. Residents deserve to know that utilities are being regulated adequately, and high-risk gas lines are being inspected and maintained properly.”
After a Sept. 9 explosion and fire on a 54-year-old segment of Pacific Gas and Electric Co.’s (PG&E) 30-inch diameter high-pressure pipeline, Hill said his major priority is “to make sure utility ratepayer dollars are being used to repair the high-risk pipelines that utilities say they are going to repair.”
Hill voiced concerns that consumer groups and others are raising about allegedly too much reliance by the CPUC and other government agencies on inspection work and reports done by the utilities. “We need to make sure there is sufficient CPUC inspection of the utility transmission pipeline system. I would also like to know more about what the CPUC is doing about high-risk and dangerous gas lines since [PG&E’s] Top-100 list released earlier did not include any of the lines at high risk to public safety.”
California regulators last Thursday formally ordered continuing investigations of various aspects of the catastrophe in which seven people died, and established an independent review panel to be paid for by PG&E.
CPUC action came in the wake of PG&E making more information available on its recent history of the highest priority maintenance and repairs on its extensive transmission pipeline system, which is concentrated in the northern two-thirds of the state. The information, however, has not revealed anything new about Line 132, or the pipeline segment that failed.
The National Transportation Safety Board (NTSB) continues to lead the major investigation into the cause of the pipeline failure. Mark Toney, executive director of consumer group The Utility Reform Network (TURN), said PG&E is clearly the entity responsible for the pipelines’ safety and maintenance, and as such, it “has more than enough money to do this.”
The regulators’ action provides for the independent review panel to be selected by CPUC President Michael Peevey and confirmed by the full five-member commission, and it is to be created in the next two months. It is empowered to gather facts and make recommendations to the CPUC as to whether there is a need for the general improvement of the safety of PG&E’s gas transmission pipeline system, which varies in size from four-inch to 42-inch diameter lines.
PG&E has made public its maintenance/inspection prioritization, but had not disclosed how it has been identifying and dealing with high-risk portions of the 6,438 miles of transmission pipelines in its system.
“Hundreds of automatic over-pressure control valves, installed where appropriate in the transmission system, protect pipelines from exceeding their maximum pressure design limits,” PG&E said in a description of its backbone system. Gas supplies fed northerly through the three transmission pipelines traversing the peninsula are fed from Milpitas in the far southeast part of the San Francisco Bay. Those supplies can originate from storage, Canada, the Rockies or the Southwest, all of which have connections to PG&E’s system.
The transmission pipeline system is dotted with sensors that feed information about pressure, flow rates and other operating information to the PG&E gas control center in San Francisco. The utility has said the control center has the capability to shut down certain pipeline systems via remote control. The segment that failed in San Bruno did not have this remote shutdown capability, and it took utility field personnel an hour and 46 minutes to manually shut off the flow of gas in Line 132 immediately following the explosion.
“While the NTSB conducts its investigation into the cause, we must do our part to examine our own regulatory processes, shore them up where necessary and restore public confidence in our utilities’ infrastructure,” said CPUC Commissioner Timothy Alan Simon, the lead California regulator on natural gas issues. Simon suggested that additional investigative work may be needed by the CPUC and the state legislature in addition to the independent review panel that the state commission created Thursday.
In dissecting the information made public in the list of top 100 projects that PG&E made public last Monday, only one project had been indicated as completed and five more as either in the engineering/planning or construction phases. The vast number of segments and projects involving more than 90 pipeline segments were either at one of the two earliest levels of attention: “monitoring” (four projects involving 22 segments) or “initiated” (37 projects involving 72 segments).
The pipeline segment in San Bruno that failed on Sept. 9 was not on the list. “We need to get to the bottom of how PG&E has been inspecting and doing the work on pipelines, particularly when they’ve had the money to do so,” said TURN’s Toney.
The utility has established a hotline for customers to call in with any questions and concerns about transmission pipelines in their neighborhoods, and it made public the list of priority projects and how PG&E juggles the prioritization and repair/replacement work. Separately, Sempra Energy’s San Diego Gas and Electric Co. (SDG&E) said it plans to provide “additional customer safety communications” for those located near gas transmission facilities.
PG&E’s pipelines typically operate at pressures between 100 and 1,040 psig (pounds per square inch gauge), the utility said. Pressures depend on the size and physical characteristics of the pipelines. Federal limits for transmission pipelines such as Line 132 are set at 400 psi, and PG&E has used 375 psi as its operating limit. Since San Bruno it has lowered pressures in the San Bruno area to 300 psi.
In addition to the ill-fated Line 132, three other transmission pipelines serving the peninsula region south of San Francisco have been reduced to 300 psi — Lines 100, 101 and 109 — a PG&E utility spokesperson told NGI.
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